Writing instrument



FIG. 1 shows a side view of my design for a writing instrument;

FIG. 2 shows a side view thereof rotated 90° with the writing tipextended;

FIG. 3 shows a side view thereof rotated 90°;

FIG. 4 shows a side view thereof rotated 90°;

FIG. 5 shows a rear end view thereof; and,

FIG. 6 shows a front end view thereof.

The ornamental design for a writing instrument, as shown and described.